The present invention relates to an arrangement for coupling a rotary shaft with a rotary member such as a V-belt pulley, a flat belt pulley and a brake drum used in a transmission for an agricultural machine or the like.
In recent years, a rotary member used to transmit relatively light loads such as a V-belt pulley or a flat belt pulley has been made by pressing a metal plate such as a steel plate. There are various known means for fixedly mounting such a thin-walled rotary member on a rotary shaft. One of them is known as projection welding in which projections are formed on a flange surface integral with a boss fixed to a rotary shaft and an electric current is passed through the projections to generate heat while pressing one side of a rotary member against the projections so that the projections will melt while being crushed, thus welding the rotary member and the rotary shaft together.
Other known methods are to apply paddings to the joint between the rotary member and the boss by use of a welding rod or to weld by use of a hard solder.
The projection welding is advantageous in that the coupling structure is simple and the welding can be done automatically with little temperature rise which might otherwise cause the rotary member to be deformed by heat. But the projection welding is unreliable because the objects are welded together only through projections having a small joint area and the welding condition tends to be influenced by the shape and size of the projections.
A fairly large bond strength may be obtained by welding by use of a welding rod or a hard solder. But in both methods, the welding area has to be heated to a high temperature. This might cause the deformation of the rotary member. Also, it is difficult to weld two different kinds of metals together with these methods.